The present invention relates optical communications, and, more particularly, to remote sensing based on optical fiber delivery and collection.
In optical spectroscopy based sensing technologies, light sources, photodetectors and other active components, e.g. temperature controller, air pump, and ventilation, are usually included in the sensor heads on situ. If the sensors are required to operate in a severe environment, active components need additional environmental control facilities to maintain appropriate conditions, such as temperature, humidity, pressure etc. to guarantee proper operation of the sensors. And in some cases, it might be impossible or very hard to provide power supplies on site.
Complicated environmental control systems are equipped with or integrated in the sensors, which consumes more power and make the whole systems more bulky, hard to deploy in limited space and hard to maintain. Another solution is to launch the light beam into free space from a remote site, aim the light beam at the target. After interference with the target, the light beam is detected at another remote site or is reflected back by a mirror to the original remote site. In this case, the light path has to be straight and free of any obstacles, otherwise the light might be blocked, resulting in sensor failure. Therefore it has high requirement on sensor deployment.
Accordingly, there is a need for remote sensing based on optical fiber delivery and collection.